Traditional safe-productive criteria for isoperibolic homogeneous semi-batch processes fail to consider the thermal stability of reacting system in case of cooling failure. In this paper, a new variable, normalized objective sensitivity S(theta(MTSR))(phi), is defined. The variation of the dimensionless MTSR0 and S(theta(MTSR))tau(i) is studied based on multiple operational parameters. A new generalized criterion is proposed, which could predict when the course of reaction enters the QFS region and simultaneously does not enter the region where the reacting system is thermally unstable. The lowest threshold corresponds to the condition where S(theta(MTSR))(phi) exhibits a sharp maximum value, and the highest threshold corresponds to the condition where MTSR is equivalent to MAT. This new safe-productive region is defined as a modified QFS region. Comparison between this new generalized criterion and other criteria is carried out and a good agreement is found. Based on the new generalized criterion, a general optimization algorithm for determining the modified QFS region, especially the optimized dosing time and jacket temperature in this region, is developed and used with limited kinetic information. (C) 2017 Elsevier B.V. All rights reserved.